Local sensing with the multilevel ac Stark effect

Schneider, A., Braümuller, J., Guo, L., Stehle, P., Rotzinger, H., Marthaler, M., Ustinov, A. V. and Weides, M. (2018) Local sensing with the multilevel ac Stark effect. Physical Review A, 97, 062334. (doi:10.1103/PhysRevA.97.062334)

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Abstract

Analyzing weak microwave signals in the GHz regime is a challenging task if the signal level is very low and the photon energy widely undefined. A superconducting qubit can detect signals in the low photon regime, but due to its discrete level structure, it is only sensitive to photons of certain energies. With a multilevel quantum system (qudit) in contrast, the unknown signal frequency and amplitude can be deduced from the higher level ac Stark shift. The measurement accuracy is given by the signal amplitude, its detuning from the discrete qudit energy level structure, and the anharmonicity. We demonstrate an energy sensitivity in the order of 10−3 with a measurement range of more than 1 GHz. Here, using a transmon qubit, we experimentally observe shifts in the transition frequencies involving up to three excited levels. These shifts are in good agreement with an analytic circuit model and master equation simulations. For large detunings, we find the shifts to scale linearly with the power of the applied microwave drive. Exploiting the effect, we demonstrated a power meter which makes it possible to characterize the microwave transmission from source to sample.

Item Type:Articles
Additional Information:This work was supported by the European Research Council (ERC) under the Grant Agreement No. 648011, Deutsche Forschungsgemeinschaft (DFG) within Project No. WE4359/7-1, the Initiative and Networking Fund of the Helmholtz Association, and the state of Baden-Württemberg through bwHPC. We acknowledge financial support by the Carl-Zeiss-Foundation (A.S.), the Landesgraduiertenförderung (LGF) of the federal state BadenWürttemberg (J.B.), and the Helmholtz International Research School for Teratronics (J.B.). A.V.U. acknowledges partial support from the Ministry of Education and Science of the Russian Federation in the framework of Contracts No. K2-2016-063 and No. K2-2017-081.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Weides, Professor Martin
Authors: Schneider, A., Braümuller, J., Guo, L., Stehle, P., Rotzinger, H., Marthaler, M., Ustinov, A. V., and Weides, M.
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:Physical Review A
Publisher:American Physical Society
ISSN:2469-9926
ISSN (Online):2469-9934
Copyright Holders:Copyright © 2018 American Physical Society
First Published:First published in Physical Review A 97:062334
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher
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